It is known that misconnections between telephone communications circuits can possibly occur in bidirectional line-switched ring transmission systems under ring node failure conditions. Accordingly, arrangements have been devised to prevent such misconnections. Specifically, the prior known arrangements employ a so-called squelching mechanism at the ring node which includes either the communications circuit entry or exit point on the ring that has a communications circuit terminating in a failed ring node. Although the occurrence of a communications circuit misconnection, intelligible or otherwise, for any duration, however short, is extremely undesirable and is to be avoided, the known arrangements are effective only to prevent so-called "long term" misconnections. "Short term", or transitory, misconnections am still a real possibility.